Storage tanks and storage systems are manufactured and used to contain and isolate a wide variety of liquids, solids and chemicals. Storage tanks and storage systems also are used to prevent leakage of the contents of storage tanks ("stored materials") into the environment. The term "environment" includes, but is not limited to, the physical and chemical surroundings of the stored materials. Thus, storage tanks are used to prevent leakage of the stored materials into the immediate surroundings including, but not limited to, earth, water and air. Storage tanks also are used to prevent leakage of stored materials and materials about to be stored in storage tanks (collectively, "contents of storage tanks") into the self-same contents of storage tanks. Spillage or leakage of contents of storage tanks may occur during filling and removing the contents of storage tanks. Several varieties of storage tanks are deployed nationally and internationally, both above and below ground, for storage of stored materials.
Most storage tanks share a common structure and cooperation of structure for filling the storage tanks with stored materials, and for removing the contents of storage tanks from storage tanks. The commonality of structure includes, but is not limited to, a storage tank having an orifice for filling the storage tank with stored materials and for removing stored materials from the tank. In many conventional storage tanks, the orifice for filling and removing the contents of storage tanks is housed in an overfill reservoir which is permanently installed in the storage tank, frequently within a permanently installed manhole of the storage tank. Overfill reservoirs also are known as piping reservoirs, seepage accumulators, catchment basins, sumps and containment vessels (collectively, "reservoir" or "reservoirs"). Piping is connectable to an apparatus installed in the orifice to fill the storage tank or remove stored materials from the storage tank. The overfill reservoir may be designed to accumulate spillage and overfill of the contents of storage tanks which may occur during filling or removing the contents of storage tanks. While many reservoirs are permanently installed in storage tanks, some reservoirs are located adjacent to storage tanks. Reservoirs that are permanently installed in a storage tank usually are located near the gravitational top of the storage tank, and may be accessed through hinged lids installed on manhole assemblies in which reservoirs are located. Any number of additional devices may be included in, or added to, overfill reservoirs for communication between the storage tank and the manhole assembly, including, but not limited to, devices for venting, heating stored materials (such as diesel fuel), varying the size of the orifice through which the storage tank is filled with stored materials, preventing siphoning, venting, leaking, and other accouterment associated with the composition of the particular stored materials.
Additionally, the contents of storage tanks may be deemed hazardous or toxic. The structure and cooperation of structure of storage tanks, any manhole assemblies installed on storage tanks, and containment reservoirs designed in connection with hazardous and toxic materials, or in which the contents of storage tanks are required to be maintained in a pure, isolated, or pristine state, may be subject to standards and codes in the United States promulgated by state and federal agencies, or promulgated by independent agencies and associations such as Underwriters Laboratories ("UL"), American Petroleum Institute ("API"), American National Standards Institute ("ANSI"), American Water Works Association ("AWWA"), and the American Society of Mechanical Engineers ("ASME") (collectively, but not exclusively, "Standards Agencies"). Standards and codes published by Standards Agencies ("Standards") exist in countries other than the United States, and it is likely that more nations will impose standards and codes as concerns grow about toxicity, handling hazardous materials, and the effect on the environment and on people of mishandling hazardous and toxic stored materials.
To achieve the express and implicit requirements of one or more of the current Standards, particularly those in connection with toxic or hazardous stored materials, it is useful if overfill reservoirs extend a predetermined distance below the innermost internal wall of storage tanks. The purpose of locating the overfill reservoir below the innermost internal wall of storage tanks is to provide additional insulating and isolating protection within the confines of the storage tank of the overspilled contents of storage tanks, a result often referred to as "internal containment." In part to achieve internal containment of overspilled contents of storage tanks in containment reservoirs, storage tanks have been designed with at least one inner wall, and often more than one inner wall, the latter storage tank often described as a "double wall" storage tank. In addition, secondary containment of spillage is achieved by designing piping connections which contribute to secondary internal confinement.
To the extent that internal containment reservoirs are not permanently installed components of a storage tank, manufacturers of storage tanks may be required to conduct special independent testing, or obtain special certification, from one or more of the Standards Agencies that the overfill containment reservoir satisfies certain standards, or the demands of users of storage tanks. The industry objective of users of storage tanks is for tanks which provide as much secondary containment as possible, not only to satisfy Standards Agencies, but also to reduce the possibility of contamination to the environment due to spillage of the contents of storage tanks. In addition, the Standards do not permit a storage tank already deployed in field use to be retrofitted with an internal containment reservoir without violating prior certification of construction compliance with the construction standards of the Standards Agencies.
The present invention relates to an apparatus and method which is useful in retrofitting existing storage tanks, particularly storage tanks already field deployed, with an internal containment reservoir which can be both installed in the field and removed in the field. The present invention also relates to an internal containment reservoir which provides the advantages of secondary containment of stored materials due to spillage. In addition, the present invention relates to a removably insertable internal containment apparatus which provides for the spillage protection comparable to double wall storage tanks themselves, and which meets the express, implicit and likely future Standards of the Standards Agencies. Currently, there is no known device which meets the standards and codes of the Standards Agencies for an overfill containment reservoir which permits field retrofitting of existing and already field deployed storage tanks with an internal containment reservoir.
What is needed, therefore, is a removably insertable containment reservoir which, following installation in a storage tank manhole assembly, is located within the storage tank in such a manner as to satisfy the demands of users of storage tanks for an internal containment reservoir which provides for the spillage protection comparable to double wall storage tanks themselves. What also is needed is a removably insertable internal containment reservoir which meets the express, implicit and likely future Standards of the Standards Agencies for internal containment of spillage.
In light of the above, it is an object of the present invention to provide an apparatus, and method of manufacturing and installation in a storage tank, for an removably insertable containment reservoir which, following installation in a storage tank manhole assembly, is located within the storage tank in such a manner as to provide internal containment of spillage.
It is another object of the present invention to provide a removably insertable internal containment reservoir which provides for the spillage protection comparable to double wall storage tanks themselves.
It is yet another object of the present invention to satisfy the express, implicit and likely future Standards of the Standards Agencies.
It is another object of the present invention to provide a removably insertable internal containment reservoir which is easily retrofitable in connection with existing field deployed storage tanks.
Yet another object of the present invention is to provide a removably insertable internal containment reservoir, and a method for manufacturing a removably insertable internal containment reservoir, which respectively are easy to use and to practice, and which are cost effective for their intended purposes.
These and other objects, features, and advantages of such a removably insertable internal containment reservoir will become apparent to those skilled in the art when read in conjunction with the accompanying following detailed description, drawing figures, and appended claims.